1. Field of Invention
The present invention relates to sprinkling technology, in particular to a rotary spray device which is mainly applied in fire fighting field, and more specifically to a spray device used in automatic fire extinguishing system and in other spray applications such as spray dust removal, spray drying, spray combustion and spray irrigation.
2. Description of Related Arts
Conventional rotary sprays such as a centrifugal spray caused by forming film with a rotary disk, its rotational power comes from a motor. However, the motor driven system has a complex structure, a large volume, and needs a rotational power externally provided. Some rotary sprinkling devices driven by fluid, such as a rotary irrigation device, generate rotational sprinkling spray by impacting rotary wheel blades only with a water jet reaction force or with water flow to drive a spray nozzle disk, as disclosed in Chinese patents No. 03245269.1 and No. 99216638.1. Since they have a relatively large volume and rotational inertia, they rotate slowly, sprinkle or spray big liquid drops, and is difficult in miniaturization, which cannot meet the strict requirements of strong force and fine atomization.
In the fire fighting field, conventional water mist spray heads or fine water mist spray heads are fixed type spray heads. It is difficult for the fixed type spray head to uniformly and completely cover all fire in a whole space, and this affects the fire extinguishing effect. A Chinese invention patent No. 200510034232.X discloses a rotary spray fire extinguishing gun. Oblique slit-type water outlets arranged in fan blade shape are provided at the front end of the water nozzle body of the gun. The water nozzle body is rotated under the reverse impact force generated from spraying water through the oblique slit. The gun may sprinkle rotatably and uniformly. However, it has a large structure, rotates slowly, and sprays large water stream and large water drops, and thus cannot appropriately form mist and are not suitable for extinguishing oil fire.
The fine water mist fire extinguisher extinguishes fire on the basis of a phase change mechanism of water mist minute drop quick evaporation, rapid cooling and oxygen depriving smother fire extinguishing. It only uses one of several to ten odd of water used for conventional water spray and sprinkling fire extinguishing to extinguish large-scale fire relatively quickly. However, the basis achieving excellent fire extinguishing performance with the minute drop phase change is that a lot of fine water mist must be produced quickly and which fully absorb heat. The evaporation speed and heat absorption efficiency of water drops are inversely proportional to the effective area covered by water drops. Therefore, superfine atomizing and fully mixing with hot air are the keys to efficiently extinguish fire with fine water mist. The conventional pressure atomization small circular hole fixed spray mode has the following disadvantages which are difficultly resolved, e.g. a contradiction between flow rate and fine atomization and a contradiction between fine atomization and spray momentum. Therefore, the performance of conventional fixed fire fighting spray head is not ideal.
Similar to the requirements for extinguishing fire with the fine water mist, the substantive purpose of the spray drying and spray combustion is to quickly vaporize a large amount of liquid. In order to achieve this purpose, water is required to atomize into fine mist and to spray mist drops to a whole space, so as to be completely mixed with air, and so that the water droplets may fully contact with air to absorb more heat from air and then be vaporized into gas. The rotary spray can provide heat transfer conditions of allowing rapid evaporation of liquid mist. In addition, a wet dust removal requires small diameter of spray drops, a high speed, a full contact between the spray mist and fume or fine dust to increase the colliding capture rate to dust particle, and these features are suitable to using the rotary spray. How to use and exert the advantage of applying the working principle of the rotary spray in the above fields, to develop a simple, reliable fluid dynamic rotary spray device to meet the requirement of energy saving and environment protection, is a problem to be urgently solved.